Adjustable tension control means for microscopes

ABSTRACT

Coarse adjustment tension control means have been provided in a microscope in connection with the coarse adjustment control to permit the regulation of friction upon the coarse adjustment according to the users focusing preference and as well by the same control means permit frictional locking of the coarse control mechanism to the vertically-adjustable block on the vertically extending arm and the specimen platform so that it need not float or settle by gravity. This tension control adjusts for wear upon the coarse control and gears. A turn-knob is provided upon a gear housing extending through the main block that is actually adjustable upon a supporting bracket for the coarse adjusting pinion gear that meshes with a rack on the upstanding arm of the microscope and this knob engages with a plurality of short rods that slide through the bearing support plate by a turn knob and engage with a longitudinally shiftable ring having a plastic friction washer adapted more or less for engagement with a cooperating flange of the coarse adjustment gear case to thereby control the tension and permit the locking of the coarse adjustment control parts in their adjusted positions.

United States Patent Berliner et al.

[11] 3,826,559 [451 July 30, 1974 ADJUSTABLE TENSION CONTROL MEANS FOR MICROSCOPES [75] Inventors: Emanuel R. Berliner, New York;

Harukichi Ishii, Tokyo, Japan [.73] Assignee: Bristoline Inc., Island Park, NY.

[22] Filed: Jan. 3, 1973 [21] Appl. N0.: 320,707

2,560,169 7/1951 Gradisar 350/84 X 2,820 396 l/l958 Prcssey 350/84 3,355.955 l2/l967 Aller 350/86 X 3,451,739 6/1969 Fitzglbbons 350/84 Primary Examiner-David H.'Rubin Attorney, Agent, or Firm-Laforest S. Saulsbury, Esq.

[5 7] ABSTRACT Coarse adjustment tension control means have been provided in a microscope in connection with the coarse adjustment control to permit the regulation of friction upon the coarse adjustment according to the users focusing preference and as well by the same control means permit frictional locking of the coarse control mechanism to the vertically-adjustable block on the vertically extending arm and the specimen platform so that it need not float or settle by gravity. This tension control adjusts for wear upon the coarse con trol and gears. A turn-knob is provided upon a gear housing extending through the main block that is actually adjustable upon a supporting bracket for the coarse adjusting pinion gear that meshes with a rack on the upstanding arm of the microscope and this knob engages with a plurality of short rods that slide through the bearing support plate by a turn knob and engage with a longitudinally shiftable ring having a plastic friction washer adapted more or less for engagement with a cooperating flange of the coarse adjustment gear case to thereby control the tension and permit the locking of the coarse adjustment control parts in their adjusted positions.

4 Claims, 7 Drawing Figures PATENIEDJUUOIBH 3 826 559 mnims I FBG,E

PATENTED 3.826.559

SHEEI a 0? 5 FIG.3A

PATENTED JUL 3 01974 SHEET 5 BF 5 mom mom

mm NON ADJUSTABLE TENSION CONTROL MEANS FOR MICROSCOPES THE SPECIFICATION This invention relates to microscopes and more particularly to the coarse adjustment control means therefor.

A principal object of the present invention is to provide in a microscope an adjustable tension control means fo use with a coarse adjustment mechanism to reduce the amount of play between the microscope adjusting parts so that the specimen platform cannot readily float or settle by gravity from focus with the microscope lens system once the proper focus has been established.

Another object of the invention is to provide in a microscope having a coarse adjustment, a simple turnknob arrangement that is concentrically carried by the coarse adjustment and which will effect frictional engagement between the pinion gear case of the coarse adjustment mechanism and the vertically-adjustable main block, but is operable not only to effect frictional control between the parts but also to provide a locking device by which the specimen platform can be locked against flotation for the taking of photographs of the specimen.

It is another object of the invention to provide a combination coarse and vernier control arrangement of a microscope with a frictional coarse and lock device that can be adjusted to suit the users focusing preference which has an adjustable stop means for controlling the amount of frictional control or the locking of the parts that can be effected by the friction control device.

For a better understanding of the invention, reference may be had to thefollowing detailed description taken in connection with the accompanying drawing, in which:

THE FIGURES FIG. 1 is a perspective view of binocular microscope to which the adjustable tension control of the present invention has been adapted.

FIG. 2 is a four-way exploded view in perspective of the microscope control parts for raising and lowering the specimen slide support and of the adjustable tension control parts forming a part thereof.

FIG. 3 is an enlarged sectional view taken along line 33 of FIG. 1 and through the adjustable tension control of the microscope coaxial coarse adjustment unit with the friction parts of the tension control released from engagement with the pinion gear case.

FIG. 3A is a similar longitudinal sectional view taken generally along the same line 33 of FIG. 1, but with the tension control parts are locked in frictional engagement with the pinion gear case with the adjusting parts and scale located at the opposite side of the microscope arm from the tension control parts being generally shown in full or fragmentation.

FIG. 4 is a transverse sectional view taken through the tension control wheel and internal parts thereof as viewed along line 4-4 of FIG. 3 when the tension control parts are free of engagement with the pinion gear case.

FIG. 4A is any enlarged transverse view taken along line 4a-4a of FIG. 3A with a tension control wheel adjusted to a position in locking engagementwith the gear case.

FIG. 5 is an enlarged exploded view of the microscope coaxial coarse adjustment unit parts and withdrawn from one side of the square metal block that supports a coarse and fine adjustment assembly and lying forwardly of the overhang portion of the upstanding microscope arm.

DETAILED DESCRIPTION OF THE INVENTION Refering now particularly to FIG. I, 20 represents a binocular microscope that comprises generally a flat bottom base 21 to which is connected an upstanding arm 22 that has an overhang support fitting portion 23 to which a binocular lens assembly 24 with its lens tubes 26 and 27 projecting upwardly in an inclined manner and with the lens tube 27 having a focusing knob 8 so that the user of the microscope can view with both eyes through a system of lenses and prisms provided in the binocular assembly 24 to observe a specimen on a microscope slide indicated generally at 29 and carried upon an adjustable slide plate platform 31 and through any one of a series of outlet lens assemblies 32 and 33 carried by a turntable 34 on the underside of the lens assembly support portion 23 of the upstanding arm 22 that overhangs the platform 31. The outlet lens assemblies 32 and 33 depend downwardly and laterally outwardly generally at degrees apart with three of these assemblies attached to the turntable 34, with but two lens assemblies being shown, there being usually three, and so-angled downwardly and outwardly from the underface of the turntable 34 and from the axis of the turntable 34 being angled from the axis of the lens assembly support portion 23, that one at a time the lens assemblies 32 and 33 and any other lens assembly that might desirably be used at the third location on the turntable 34 may be axially aligned with a hole36 in the platform 31 so that the specimen carried on the slide 29 overlying the hole can be observed. Carried on the base 21 and extending upwardly therefrom is a light device 37 that directs light rays upwardly through the hole 36 and into any one of the outlet lens assemblies 32 and 33 that may be aligned with the hole 36 in the platform 31 wherein the specimen carried by the slide 29 may appear translucent.

Attached to the underside of the platform 31 is an adjustable light condenser assembly through which the light rays from the light device 37 on the base 21 may pass before entering the opening 36 of the platform. This condenser assembly is adjustable in a manner to be described later herein. Platform 31 has a fore and aft movable transverse beam 41 with a front plate 42 fastened thereto and which carries a jaw member 43 that extends forwardly against which one edge of the specimen slide plate 29 is retained, with its opposite edge held in place thereagainst by a spring-biased bell-crank finger 44 that can be released by depressing upstanding handle 46 with the slide plate 29 retained between the jaw 43 and the finger 44. Plate 42 can follow the fore and aft movement of the beam 41 and with the front plate 42 being in the form of an adjustable cross-slide laterally adjustable over the front face of the transverse beam 41 and to which the finger and jaw assembly 43 is actually secured so that a transverse movement of the slide 29 thereby can be effected.

The transverse beam 41 has, on one side of the platform a forwardly'extending guide-way arm 47 that is worked by a rack and pinion turn knob arrangement 48 so that the guideway arm 47 can be slid along a dove tail member 49 on the side of the platform 31 fowardly until the end of the guide arm 47 may engage with an outwardly extending pin stop 51. Through an effective rack and pinion arrangement, not shown, cross slide 42 on the fore and aft movable beam 41 can beadjusted to adjust the slide 29 carried between the jaw 43 and the finger 44 sidewise in a desired amount and which is operated by a turn knob 52 underlying the beamadjusting knob arrangement 48.

The depending platform 31 is fixedly carried on a depending bracket or stage holder 53 that is in turn adjustably carried for vertical adjustment upon the outer face of a coarse and vernier adjustment assembly 54 that is in turn adjustable on the upstanding arm 22. This adjustment assembly 54 has a coarse adjustment knob 55 for effecting adjustment of the assembly 54 upon the arm 22 and a vernier adjusting knob 56 for effecting the adjustment of the platform bracket 53 coaxially arranged with the coarse adjusting knob 55. At the oppo site sideof the microscope extending outwardly from the adjusting assembly 54 are knobs 55 and 56 that work in unison with the respective knobs S and 56 and on which the vernier knob 56 has a vernier scale 57 that works with reference to an arrow indication on the coarse knob 55'.

it is particularly in connection with this vernier and coarse adjustment assembly 54 in which the present invention is incorporated in the form of a tension control wheel arrangement 58 shown in FIG. 1, lying on one side of the assembly 54 and which will be later described in detail, can be adjusted to frictionally retain platform 31 in its adjusted position against the action of gravity when the wheel 58 is turned to effect a tightening action upon the internal parts of the coarse and vernier adjusting assembly 64. This adjusting assembly 54 and its parts are seen in the exploded view of FIG. 2 taken with the longitudinal sectional and enlarged assembly views of FIGS. 3, 3A, 4, and 4A.-A detailed description of the adjusting assembly and its parts will now be made, with particular reference to their show ing in the exploded view of FIG. 2.

The upstanding arm 22 is rigidly secured to the base 21 from the hollow underside of the base in any suit-v able manner that provides a rigid connection therewith at the lower end of the arm and against lateral and vertical displacement therefrom. Beneath the overhanging binocular microscope supporting arm portion 23 is a flat vertical attaching face 61 having three screw holes 62 vertically spaced from one-another for the attachment thereto of a rack guide 63 by screws 64.

Pins 66 further connect and align the guide 63 on the surface61 by entering the holes 66 therein. This rack gear guide 63 is generally'of dove-tail section with oppositely inclined guide surfaces upon which slides a main metal block 67 that holds the coaxial coarse and fine adjustment assembly 54 and by which the block 67 is vertically worked up an down upon the guide 63 and the support arm 22. The rack gear guide 63 is received within a vertically-extending corresponding dovetail section slot 68 on the rear face of the block 67. The rack gear guide 63 has a vertically extending groove 69 centrally aligned on its front face within which is secured rack gear 71 by screws 72 to be carried thereby and with the screws 72 respectively entering threaded holes 73 in the gear guide 63. The front face of the metal block 67 has a'vertically -extending closed bottom slot 74 and an integral forwardly-extending side edge 76 with a vertically-extending slot 77 running throughout the extent of its inner face serving to carry small ball-bearing guide rods 78 between which runs a series of ball bearings 79 held captive within ball bearing support plate 81 for the connection therewith of a fine adjustment slide 82 having a groove 83 confronting groove 77 in the block side edge extension 76 and adapted to contain side rail rods 84 in which the balls 79 will run. Top and bottom stop pins 86 and 87 are threaded into the slide 82 and engaged by the ends of the ball-support plate 81 to limit the vertical adjustment of the fine adjustment slide 82 and to hold balls 79 against vertical displacement from their confinement inbetween rods 78 and 84.

In the opposite side of the vertical fine adjustment slide 82 is a groove 88 that contains parallel wall guide rods 89 in which a series of small ball bearings 91 travel while being contained within a ball-support plate 92 and working in spaced guide-rods 93 carried in a groove 94 of a detachable block metal guide 95 opposing the side edge extension 76 and secured on the face of the square metal main block 67 by a series of fastening screws 96 entering holes 97 in the front face of the block 67. Top and'bottom stop pins 98 and 99 are threaded into the fine adjustment slider 82 for engagement by the ends of the ball support plate 92 to confine the balls 91 between the slider 82 and detachable side block guide 95. These parts assembled upon the square block 67 will contain the fine adjustment slide 82 for fine vertical and vernier adjustment upon the main block 67. The upper end of the slide 82 has connected thereto for movement therewith, upon the rear face thereof and lying within the cut-away opening 74 of the main block 67, a short metal block 101 the lower end face of which has a small opening, or indentation not shown, for receiving height pin 102 carried'upon the upper edge of fine adjustment cam lever 103 pivotally attached by a screw 104 and a spacing washer 105 to the metal block 67 within the cutaway opening 74 at cutaway edge 106 thereof so that lower end 103 will be engaged by a face of an enlargement or flange 107 of a vernier adjusting shaft 108 that forms part of an assembly that extends through a laterally extending large opening 110 in the block metal 67 as fine threads 109 at one side of the flange 107 that have threaded engagement within a threadedhole 111 of a main pinion gear case-part 112 that is threadedly connected by its threaded end 113 in a threaded opening 114 containing a washer 116 of a pinion gear case part 117 having a partial gear formation 118 extending thereabout which has mesh with the rack gear 71 when the assembly including the parts 108, 112, 117 are mounted and held within the through-opening 109 of the metal block 67 by means to be described, for rotation of the gear 118 by knobs above described for the purpose of effecting coarse adjustment of the block 67 upon the arm 22 and the vertical adjustment of the fine adjusting slide 82 on the block 67 by the vernier adjusting shaft 108.

The gear case part 112 has flange 119 that abuts the threaded open end 113 of the gear casing part 117 and which also abuts a bearing support plate 121 secured over the opening 109 by screws 112 entering holes 123 in the right side face of the metal block 67.

The gear casing part 117 is somewhat similarly supported on the opposite side of the opening 109 of the block 67 by an affixing bearing support plate 128 in which gear casing part 117 is journaled along with a plastic ring washer 125 and abutting the end of a thin axially adjusting ring 124 against annular shoulder 126 of gear casing part 117 to minimize wear and to provide frictional engagement therewith. This adjusting ring 124 is contained in a circular recess 127 of thick metal bearing support plate 128 provided on its opposite face with a reduced diameter threaded sleeve portion 129. This support plate 128 is fixed to the opposite side face of block 67 by fastening screws 131 and the recess 127 will contain therein adjusting ring 124 with its oppositely extending sleeve portion 124' against the end of which plastic friction ring 125 abuts. With these parts 124 and 128 assembled upon the block 67 with the screws 131, the gear casing part 117 with the vernier adjusting shaft 108 is supported for rotation to provide for coarse and fine adjustment of the block 67 upon the upstanding arm 22.

Within this bearing support plate 128, there are provided three small holes 132 that extend into its circular recess 127 and in which there is slidable respectively short friction control rods 133 entering recess 127 of the support plate 128 for frictional engagement with the inner face of the thin adjusting ring 124 and serving when forced inwardly into the recess against the ring 124 to provide frictional restrictive engagement therewith and of the plastic ring 125 with the shoulder 126 to thereby lock the gear case part 117 against turning movement in the block 67 and the lowering of the block 67 upon the arm 22 such as would be affected by gravity of the specimen platform that would put the specimen out of focus with the microscope lenses. This is the critical part of the assembly for effecting friction control locking of the parts which when used with frictional control knob 58 threadedly connected by its internal threads 136 with the threaded sleeve portion 129 of the thick bearing support plate 128 and the tightening of the knob 58 thereon to force inwardly the small rods 133, takes-up lost motion between the thin adjusting ring 124 and the thick bearing support plate 128 and makes for more or less frictional engagement with the flange 126 of the gear casing part 117 to thereby lock thegear part 117 in effect to the block 67 so that vertical adjustment of the block cannot be readily effected and the lowering of the block 67 with the specimen platform 31 thereon as by gravity and weight will not be affected, so that the focus of the microscope upon the specimen for a given adjustment will be retained. it is with these frictional control parts that the novelty of this invention lies and of which further description will be made of its operation hereinafter when the description has been completed of all of the parts of FIG. 2.

A compression spring 137 is fitted into a bottom hole in the main metal block 67 and contained therein by a spring case 138 tightly fitted within the hole and closed at its bottom by a ring 139. This spring case 136 is inserted in a hole in the base 21 in the top thereof up to its flange 141. This spring 137 provides support for the block 67 against ordinary downwardly displacement thereof but the spring 137 is not under such tension as to always eliminate any settling by gravity by virtue of looseness of parts that would tend to get the specimen out of focus with the microscope lens system and does not eliminate any need for the friction control device 6 of the present invention. Spring 137 merely provides cushioning action.

Two cover plates 142 and 143 are respectively secured to the upper end of the block 67 by fastening screws 144. A stopping assembly indicated generally at 146 is provided on the upper portion of the arm 22 and supported within an indenture 147 thereat. This stop device 146 comprises a T-shaped block 148 that rests over the indenture 147 and is secured to the front face 149 thereabove by fastening screws 151. A round vertical opening 152 is provided in the block in which stop plunger 153 is locked at any vertically-adjusted position within the block 148 by a finger adjusting set screw 154 inserted into the block 148 and extending from the side thereof and adapted to engage with the surface of the plunger 153 to hold it at the desired vertical location against action of a compression spring 156. A screw 157 is inserted into the side of the plunger 153 that extends outwardly from the slot 152 for engagement with the rear plate 142 fixed to the block 67 to thereby stop the upward movement of the block 67.

Fastened to the vernier vertical slide 82 that is adjustable in the block 67 is the depending bracket stage holder 53 which has laterally extending supporting wing portions 162 and 163 extending from the opposite sides thereof onto which the specimen plate platform 31 is attached by screws entering through holes 164 and 165 thereof and up into the underface of the platform 31. This stage holder 53 will move up and down with the coarse adjustment of the block 67 and relative to the block 67 by the fine adjustment including the cam lever 103, pin 102 that engages with the underside of the short metal block 101 which also is fastened to the vertical slide 82 by screws 82' that enter threaded holes 101 in the block 101. Screws 166 vertically spaced from one-another extend through the holes 166 in the stage holder 53 and into holes 167 in the front face of the vertical slide 82.

A dove-tail section guide 168 is secured by screws 169 to the front face of the stage holder 53 and within a groove 171 thereof there is fitted a gear rack 172 that is secured by screws 173.

A condenser supporting bracket 174 having a dovetailed groove 175 is slidablymounted upon the dovetail guide 171 carried on the stage holder 53. The condenser holder carries a pinion, not shown, extending transversely within the dovetailed slot 175 and in engagement with rack 172 so that when its hand knob 176 is turned, the condenser support 174 can be adjusted vertically upon the stage holder 53 to the desired location. The condenser support 174 has a ring formation 177 into the underside of which can be fitted a condenser-supporting sleeve 178 with threads 179 by which the sleeve 178 is locked in place in the ring formation 177 by a lock ring 181 engaging the ring portion 177. The light condenser assembly 38 in turn fitted into the condenser sleeve 178 and will move vertically therewith upon the hand knob 176 being turned to adjust the light condenser relative to the stage holder 53 and to the underface of platform 31. A set screw 182 will hold the condenser assembly 38 locked in place within the condenser sleeve 178 and upon the ring formation 177.

The gear casing part 112 is threaded by its threaded end portion 113 into threaded opening 114 of gear casing part 117. The vernier shaft 108 is threaded at and has a threaded connection with the interior of the gear casing part 112 by the threads 111 thereof. The gear case part 112 is journaled in the ring support 121 and thus can turn therein and the shaft 108 can thus turn in gear case part 112. A plastic ring washer 186 is engageable with the. end-faceof the support ring 121 on the block 67 FIG. 3 to takeup wear and this ring is enclosed in a recess in the coarse adjustment turn knob 55 that is threaded upon a threaded portion 187 of the gear case part 112 against a shoulder 188 and held. thereagainst by a lock washer 189 with a set screw 191 to keep the lock nut 189 from turning from its locked position. Thus, the knob 55' can be turned as well as the knob 55 to effect rotation of the assembled gear case ports 112 and 117 and the gear 118 thereof along with other parts so that the block 67 and the platform 31 can be adjusted for coarse adjustment by the right hand as well as by the left hand to place the specimen in focus with the microscope lens system. On the right hand outer end of the vernier shaft 108 isthe vernier knob-56' having a cup-shaped part 192 secured to its inner end thereto and turnabletherewith and bearing upon its periphery a measuring scale 193 so the turning of the knob 56' will effect turning of the scale part 192.

This scale part 192 with scale 193 lies within the knob portion bearing an index mark or arrow 194 FIG. 2.

- The scale part 192 may be splined as indicated-at 195 upon reduced diameter portion 196 of the knob 56. Knob 56' is fixed against axial displacement from the outer end of the vernier shaft 108 by an end fastening screw 197 and against rotation thereover by a set screw 198.

Since the gear case part 112 is held against axial displacement, the screw threads 110 as the shaft 108 is turned, the shaft as viewed in FIG. 3 will be adjusted to the left for the purposes of working the cam lever 103 of FIG. 2 that lies in the path of movement of the flange 107 and thus effecting vernier adjustment of the slide 82 relative to the block 67 as above described. In order to limit the axial adjustment of the shaft 108, a stop screw is provided on th outerend of the gear casing part 112 as indicated at 199 that will be engaged by stop screw 201 on the reduced diameter end of the knob 56 to thereby limit the amount of the vernier adjustment. The gear casing 117 has a threaded external portion 202 On which coarse adjustment knob 55 is threaded against a shoulder 203 on the gear casing part l17,-the knob 55 having internal threads 204, FIG. 2 for this purpose. The knob 55 is locked against the shoulder 23 by a lock nut 206 that when placed in the locking position is held against rotation by a set screw 207.

Thus, when the knob 55 is turned by the left hand, the gear 118 is turned to act upon the rack 71 on the arm 22 so as to cause the main block 67 to move vertically thereupon. A washer 209 is disposed between the end of the threaded portion 129 and a recess 210 in the inner face of the knob 55 to take-up any wear therebetween.

The vernier adjusting knob 56 is secured to the shaft 108 against axial displacement therefrom by an end screw 211 and against rotational displacement thereon by a set screw 212 so that as the knob 56 is turned by the left hand the shaft 108 will be rotated and the vernier control assembly parts will be worked. A stop screw 213 is provided on the knob 56 which will engage screw head 214 on the end of the gear case part 117.

The arrangement and assembly of the parts ofv the microscope'should be such that there is very little play between the several parts. In FIG. 2, the vertical guide member 95 for the vertical block 67 has it's groove 94 deepenedto accomodate a pressure groove plate 216 which is located in the bottom of the groove 94. The parallel guide rods 93 will also lie in the groove 94 against the pressure plate 216. This pressure plate 216 is backed up by pressure screws 217 and 218 that are threaded into holes in the guideway member 95 for engagement with the .back face of the pressure plate 216 so that the pressure plate can force outwardly the rods 93, ball bearing-supporting plate 92 and the balls 91 to make for a more tight fitting assembly of these balls 91 and the balls 79 to take-up any lateral play resulting from any manufacturing undue tolerances in the manufacturing of the parts or later from wear of the parts. This pressure plate means provides for an adjustment of looseness of any of the parts in the vertical vernier adjustment.

In operation, the coarse adjustment of the specimen supporting platform 31 is effected by turning the knob 55 or the knob 55. In this manner a quick vertical adjustment and focusing of the specimen provided on the slide plate 29 is brought into focus with the binocular microscope lens system. This is effected quickly but it has been found that as a result of gravity once the platform 31 and the specimen has been put into focus and upon leaving the microscope the platform 31 with the specimen will have settled due to gravity and normally causing running of the parts so that upon returnjof the user to the microscope the specimen will have been put out of focus, thereby requiring a further adjustment of the knobs 55 and 55. Immediately after making a coarse adjustment of the knobs 55 or 55 in order to bring the specimen into proper focus, the vernier knob 56 or 56'is turned so that the most satisfactory and fine adjustment of the microscope lenses with relation to the specimen will have been effected. Thus, not only has a coarse adjustment been effected but also a vernier adjustment has been effected taking time of the user to prepare the microscope for the particular specimen being studied. Thus, in order that the coarse adjustment control can be locked there has been provided according to this inventionthe locking wheel knob 58 that is adjustable upon the threaded portion 129 of the bearing support plate 128 that is fixed by the screws 131 to the side of the main block 67 as best viewed in FIGS. 3 and 3A. This bearing support plate 128 has the three short rods 133 slidable in holes 132 in support plate 128 with their inner ends adapted to engage a pressure plate 124 that will bring a plastic washer 125 into tight frictional engagement with a flange face 126 of gear casing 117. The control knob 58 has internal thread 136 and is threaded to the threaded sleeve portion 129 of the bearing support 128 and upon being turned and engaging with the outer ends of the rods 133 from a position shown in FIG. 3 so as to be moved axially along the threaded portion 129 to a position of engagement of the friction washer 125 with the flange 126 as shown in FIG. 3A. This axial adjustment of the friction control knob 58 is continued until a stop screw 221 engages the outer face of the bearing support plate 128. A slight adjustment of the stop screw 221 can be made to limit the degree of friction placed upon the gear casing flange face 126 by the plastic washer 125 and to take-up for any wear of this washer 125 through continued use. With this knob 58 turned to cause the washer 125 to have friction grip with the gear casing 117, the gear casing will thereby be automatically locked upon the main block 67 through its bearing support 128 so that there is little opportunity for the platform supporting the specimen to lag or settle and thus the exact coarse and vernier adjustments will be maintained. Release of the knob 58 permits the user to again turn knobs 55 and 55 for further coarse and vernier adjustment.

It should now be apparent that there has been provided a friction control or lock device for use with a coarse and vernier adjustment control of a microscope that prevents the specimen and its image from floating out of focus and as well during the daily use of the microscope permit the user of the microscope to adjust the tension of the coarse control mechanism to his individual focusing preference during the daily use of the microscope. This coarse adjustment friction or lock device provides an adjustable tension control to compensate for excessive wear during continuous use of the microscope so that the specimen and its image no longer can easily float out of focus. The control device can be locked as described above in a fixed position to facilitate the taking of precise photographs with the microscope.

While various changes may be made in the detailed construction, it shall be understood that such changes shall be within the spirit and scope of the invention as defined by the appended claims.

I claim:

1. In a microscope, a base, an upstanding arm extending upwardly therefrom and overhanging the base, microscope lens assemblies fixedly mounted to the upstanding arm and a vertically-extending rack gear mounted upon the front face thereof, a main block con nected to the front face of the upstanding arm and over the rack for vertical slide adjustment with respect thereto, said main block having an opening extending laterally through the opposite side of the block, pinion gear case means extending laterally through the block opening and meshing with the arm rack and turnable to raise and lower the main block for coarse adjustment relative thereto, bearing support plates secured to the opposite sides of the main block over the laterallyextending opening and having the pinion gear case means journaled therein, a specimen slide supporting platform carried upon the front of the main block to be adjustable therewith to bring the specimen under the focus of a microscope lens assembly, a hand knob secured to the pinion gear case to turn the same, and tension control means extending between the hand knob and the gear case to regulate by friction the force required to turn the hand knob relative to the block and the lifting and lowering of the specimen slide supporting platform, said tension control means including the provision of a threaded sleeve portion extending laterally outwardly from one of the bearing support plates on the main block through which the pinion gear case extends, said one bearing support having a plurality of small holes extending through plate and parallel to the axial'axis thereof and circumferentially spaced from one another thereabout, said pinion gear case being provided with an annular radially-extending shoulder extending thereabout, friction ring means mounted on the gear case for axial adjustment thereover between the holes in the support plate and the shoulder for frictional and locking engagement therewith, short work rods respectively axially slidably adjustable in the respective small holes in the bearing support plate, and a tension control wheel threaded upon the support plate threaded sleeve portion and engageable with the short pins to apply pressure upon the ring means and the gear case shoulder when axially adjusted upon the sleeve portion toward the ring means to provide frictional or locking engagement with the gear case shoulder to thereby regulate the friction between the block and the gear case.

2. In a microscope, the combination as defined in claim 1 and said bearing support plate having a recess in its opposite face from the threaded portion thereof and said ring means being workable in the plate recess.

thereon being outwardly of the coarse control knob. 

1. In a microscope, a base, an upstanding arm extending upwardly therefrom and overhanging the base, microscope lens assemblies fixedly mounted to the upstanding arm and a vertically-extending rack gear mounted upon the front face thereof, a main block connected to the front face of the upstanding arm and over the rack for vertical slide adjustment with respect thereto, said main block having an opening extending laterally through the opposite side of the block, pinion gear case means extending laterally through the block opening and meshing with the arm rack and turnable to raise and lower the main block for coarse adjustment relative thereto, bearing support plates secured to the opposite sides of the main block over the laterally-extending opening and having the pinion gear case means journaled therein, a specimen slide supporting platform carried upon the front of the main block to be adjustable therewith to bring the specimen under the focus of a microscope lens assembly, a hand knob secured to the pinion gear case to turn the same, and tension control means extending between the hand knob and the gear case to regulate by friction the force required to turn the hand knob relative to the block and the lifting and lowering of the specimen slide supporting platform, said tension control means including the provision of a threaded sleeve portion extending laterally outwardly from one of the bearing support plates on the main block through which the pinion gear case extends, said one bearing support having a plurality of small holes extending through plate and parallel to the axial axis thereof and circumferentially spaced from one another thereabout, said pinion gear case being provided with an annular radially-extending shoulder extending thereabout, friction ring means mounted on the gear case for axial adjustment thereover between the holes in the support plate and the shoulder for frictional and locking engagement therewith, short work rods respectively axially slidably adjustable in the respective small holes in the bearing support plate, and a tension control wheel threaded upon the support plate threaded sleeve portion and engageable with the short pins to apply pressure upon the ring means and the gear case shoulder when axially adjusted upon the sleeve portion toward the ring means to provide frictional or locking engagement with the gear case shoulder to thereby regulate the friction between the block and the gear case.
 2. In a microscope, the combination as defined in claim 1 and said bearing support plate having a recess in its opposite face from the threaded portion thereof and said ring means being workable in the plate recess.
 3. In a microscope, the combination as defined in claim 1 and an adjustable stop screw carried upon the tension control wheel and engageable with the ring means to limit the axial movement of the control wheel upon the support plate threaded portion and the degree of friction upon the gear case shoulder.
 4. In a microscope, the combination as defined in claim 1 and vernier control adjustment means being carried upon the main block and operable independently of the coarse control means by a shaft extending through the gear case assembly and with a knob thereon being outwardly of the coarse control knob. 